In the field of optical data storage, a laser driver drives a current through a laser diode to cause it to emit light. When current is flowing to produce light, there is a voltage drop across the laser diode. In optical data storage applications, the desire for faster writing speeds and higher storage densities has resulted in laser diodes that drop a substantial forward voltage when operating at their peak current values. This forward laser diode drop will only increase as shorter wavelength laser diodes are introduced into the marketplace.
Unfortunately, most electronic systems run off standardized voltage supplies, which rarely change due to the large legacy of silicon components already designed to operate at these voltages. Since the laser diode is designed to achieve certain optimum performance characteristics without regard to supply voltage standards, the resulting laser diodes can have voltage requirements that make it very difficult to design laser drivers without certain compromises. The primary requirement is that the laser driver should be able to drive all the laser diodes supplied by vendors for a given application. When worst case forward voltage drop is taken into consideration, it may not be possible to drive such laser diodes with standard supply voltages, such as 3.3V or 5.0V. Since optical data storage applications usually exist in a personal computer (pc) environment, the supply voltages are generally fixed and limited, and often with a poor tolerance.
Even when a custom voltage supply is added, worst case analysis results in operation at a higher supply voltage than the laser diode typically requires, causing excess power dissipation. In a battery based environment such as laptop computers, this is highly undesirable.
Accordingly, there is a need to overcome the above discussed problems and disadvantages.